Power-up signal generator in semiconductor device

ABSTRACT

A power-up signal generation circuit includes a first power-up detecting unit, to which an external power supply voltage is applied, for activating a first power-up signal when an increase of the external power supply voltage is detected, a second power-up detecting unit, to which an internal power supply voltage is applied, for activating a second power-up signal when an increase of the internal power supply voltage is detected and a power-up signal generating unit for activating a final power-up signal in response to combination of the first and the second power-up signals.

BACKGROUND

[0001] 1. Technical Field

[0002] A power-up signal generation circuit to be applied to various kinds of semiconductor devices is disclosed.

[0003] 2. Description of The Related Art

[0004]FIG. 1 is a circuit diagram illustrating a conventional power-up signal generation circuit. The power-up signal generation circuit includes a plurality of PMOS transistors P11, P12, P13, and PCAP11, a plurality of NMOS transistors N11, NCAP11 and NCAP12 and a plurality of inverters INV11, INV12, INV13 and INV14.

[0005] The PMOS transistors P11 and P12 and the NMOS transistor N11 are coupled in series between a power supply voltage VDD and a ground voltage. A gate of the first PMOS transistor P11 is coupled to a drain thereof and a gate of the second PMOS transistor P12 is coupled to a ground voltage. A gate of the first NMOS transistor N11 is coupled to a drain thereof and a gate of the second NMOS transistor NCAP11, whose drain and source are coupled each other to a ground voltage, is coupled to the drain of the second PMOS transistor P112. The third PMOS transistor P13 is coupled between a power supply voltage and a first node node11, which is connected to the drain of the second PMOS transistor P12. An input of the first inverter INV11 is coupled to the first node node11 and an output of the first inverter INV11 is coupled to a gate of the third PMOS transistor P13 and a second node node12. A drain and a source of the fourth PMOS transistor PCAP11, whose gate is coupled to the second node node12, are coupled each other to a power supply voltage VDD. The second inverter INV12 is coupled to the second node node12. A drain and a source of the third transistor PCAP11, whose gate is coupled to an third node node13 connected to an output of the second inverter INV12, are coupled each other to a ground voltage. The third and fourth inverters INV13 and INV14 are coupled in series. An input of the third inverter INV13 is coupled to the third node node 13. The fourth inverter INV14 receives an output signal and outputs a power-up signal PWRUP.

[0006] Hereinafter, an operation of the conventional power-up detection circuit will be described as follow:

[0007] If the power supply voltage VDD applied from an external circuit is increased, a voltage level of the first node node11 is increased from VSS to a predetermined voltage level according to a current ratio of the first PMOS transistor P11, the second PMOS transistor P12 and the first NMOS transistor N11. If a voltage level of the first node node11 is increased over a threshold voltage of the first inverter INV11, since a the second node node12 is coupled to the gate of the fourth PMOS transistor PCAP11, a voltage level of the second node node12 is initially increased as much as a increased power supply voltage VDD and then is fallen to a ground voltage VSS by the first inverter INV11. The power-up signal PWRUP is transited from a low level to a high level by passing through the inverters INV12, INV13 and INV14. Namely, the external power supply voltage VDD applied to the circuit is detected and then the power-up signal PWRUP representing that an operation voltage is completely applied is outputted.

[0008] The power supply voltage VDD is finally detected by using one or more capacitor structures NCAP or PCAP. According to the conventional power-up detecting circuit as mentioned above, if the power supply voltage VDD is applied to the circuit and the applied external power voltage too slowly ramps up to its voltage level, there may be a problem that the power-up signal is not appropriately generated since the detection operation of the capacitor structure may fail on the slow voltage ramp-up. Recently, since it has a tendency that a voltage level of the power supply voltage VDD is decreased, the above problem may be more serious.

SUMMARY OF THE DISCLOSURE

[0009] A power-up signal generation circuit capable of stably generating a power-up signal in a slow power-up operation is disclosed.

[0010] An apparatus for generating a power-up signal is disclosed which comprises: a first power-up detecting unit, to which an external power supply voltage is applied, for activating a first power-up signal when an increase of the external power supply voltage is detected; a second power-up detecting unit, to which an internal power supply voltage is applied, for activating a second power-up signal when an increase of the internal power supply voltage is detected; and a power-up signal generating means for activating a final power-up signal in response to combination of the first and the second power-up signals.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above and other features of the disclosed circuits will become apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings, wherein:

[0012]FIG. 1 is a circuit diagram illustrating a conventional power-up signal generation circuit;

[0013]FIG. 2 is a block diagram illustrating a power-up signal generation circuit in accordance with one disclosed embodiment;

[0014]FIG. 3 is a circuit diagram illustrating the second power-up detecting unit in the power-up signal generation circuit of FIG. 2;

[0015]FIG. 4 is a circuit diagram illustrating the first power-up signal generating unit in the power-up signal generation circuit of FIG. 2;

[0016]FIG. 5 is a block diagram illustrating a power-up signal generation circuit in accordance with another disclosed embodiment;

[0017]FIG. 6 is a circuit diagram illustrating the second power-up signal generating unit 503 in the power-up signal generation circuit of FIG. 5; and

[0018]FIG. 7 is a timing diagram illustrating a power-up signal generation in accordance with this disclosure.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0019] Hereinafter, a power-up signal generating circuit for generating a power-up signal notifying a start point of an operation of a semiconductor device by internally detecting a power supply voltage VDD in a semiconductor device will be described in detail referring to the accompanying drawings.

[0020]FIG. 2 is a block diagram illustrating a power-up signal generation circuit in accordance with one embodiment of the present invention. The power-up signal generation circuit includes a first power-up detecting unit 201, a second power-up detecting unit 202 and a power-up signal generation unit 203.

[0021] When the first power-up detecting unit 201, to which a external power supply voltage VDD is applied, detects an increase of the power supply voltage VDD, a first power-up signal PWRUP1 is generated. The first power-up signal PWRUP1 is inputted to the power-up signal generation unit 203. The first power-up detecting unit 210 may be identically configured with the conventional power-up generation circuit illustrated in FIG. 1.

[0022] When the second power-up detecting unit 202, to which an internal power supply voltage V_(CORE) is applied, detects an increase of the internal power supply voltage, a second power-up signal PWRUP2 is generated. The second power-up signal PWRUP2 is inputted to the power-up signal generation unit 203. The internal power supply voltage V_(CORE) represents an internal power supply voltage supplied to a cell array. Also, an internal power supply voltage V_(peri) supplied to a peripheral area may be employed; however, it is preferable that the internal power supply voltage V_(CORE) of the cell array is used.

[0023] The power-up signal generation unit 203 receives the first power-up signal PWRUP1 outputted from the first power-up detecting unit 201 and the second power-up signal PWRUP2 outputted from the second power-up detecting unit 202 and finally generates a power-up signal PWRUP_SUM.

[0024]FIG. 3 is a circuit diagram illustrating the second power-up detecting unit 202 in the power-up signal generation circuit in accordance with a preferred embodiment.

[0025] The second power-up detecting unit 202 includes a plurality of PMOS transistors P31, P32, P33 and PCAP31, a plurality of NMOS transistors N31, NCAP31 and NCAP32 and a plurality of inverters INV31, INV32, INV33 and INV34.

[0026] The transistors P31, P32 and N31 are coupled in series between the internal power supply voltage V_(CORE) and a ground voltage. A gate of the PMOS transistor P31 is coupled to a drain thereof and a gate of the PMOS transistor 32 is coupled to a ground voltage. Also, a gate of the transistor N31 is coupled to a drain thereof.

[0027] The inverters INV31, INV32, INV33 and INV34 are coupled in series and an input of the inverter INV31 is coupled to a node node31 connected to a junction of the transistors P32 and N31. A gate of the NMOS transistor NCAP31, whose drain and source are coupled each other to a ground voltage, is coupled to the node node31. Herein, the NMOS transistor NCAP31 operates as a capacitor. The PMOS transistor P33, whose gate is coupled to an output of the inverter INV31, is coupled between the internal voltage V_(CORE) and the node node31. A gate of the PMOS transistor PCAP31, whose drain and source are coupled each other to the internal voltage V_(CORE), is coupled to a node node32 connecting the inverter INV31 with the inverter INV32. Herein, the PMOS transistor PCAP31 operates as a capacitor. A gate of the NMOS transistor NCAP32, whose drain and source are coupled each other to the ground voltage, is coupled to a node node33 connecting the inverter INV32 with the inverter INV33. Herein, the NMOS transistor NCAP32 operates as a capacitor. The inverter INV34 finally outputs the second power-up signal PWRUP2.

[0028]FIG. 4 is a circuit diagram illustrating the power-up signal generation unit 203 in the power-up signal generation circuit in accordance with the preferred embodiment.

[0029] As shown, a source of a PMOS transistor P41 is coupled to VDD and the first power-up signal PWRUP1 outputted from the first power-up detection unit 201 is applied to a gate of the fifth PMOS transistor P41. A source of the fourth NMOS transistor N41 is coupled to VSS and its drain is coupled to a drain of the fifth PMOS transistor P41. The second power-up signal outputted from the second power-up detecting unit 202 is applied to a gate of the fourth NMOS transistor N41.

[0030] A source of a sixth PMOS transistor P42 is coupled to VDD, its gate is coupled to VSS and its drain is coupled to the drain of the fifth PMOS transistor P41. The sixth PMOS transistor P42, which is coupled to VSS, is always turned on and is coupled to a fourth node node41. The sixth PMOS transistor P42 makes a DC path between the fourth node node41 and VDD. Namely, an initial voltage level of the fourth node node41 is maintained in VDD. The sixth PMOS transistor P42 is configured with a long channel transistor by considering a current consumption.

[0031] A drain and a source of a seventh PMOS transistor PCAP41 are coupled to VDD and its gate is coupled to the drain of the fifth transistor P41. A fifth inverter INV41 inverts a signal received through the drain of the fifth PMOS transistor P41 and outputs an inverted signal. A sixth inverter INV42 inverts a signal received through the output of the fifth inverter INV41 and outputs an inverted signal. A seventh inverter INV43 inverts a signal received through an output of the sixth inverter INV42 and outputs an inverted signal.

[0032]FIG. 5 is a block diagram illustrating a power-up signal generation circuit in accordance with another disclosed embodiment. The power-up signal generation circuit includes a first power-up detecting unit 501, a third power-up detecting unit 520 and a second power-up signal generating unit 503.

[0033] An external power supply voltage VDD is applied to the first power-up detecting unit 501 and, when an increase of the external power supply voltage is detected, a first power-up signal PWRUP1 is generated and inputted to the second power-up signal generating unit 503. The first power-up detecting unit 501 may be identically configured with the conventional power-up detecting circuit described in FIG. 1.

[0034] The third power-up detecting unit 520 includes a plurality of internal power-up detecting units 521. An internal power supply voltage V_(CORE) is applied to the plurality of internal power-up detecting units 521, respectively, and, when an increase of the internal power supply voltage is detected, a plurality of internal power-up signals PWRUP_2 to PWRUP_N are generated. The plurality of internal power-up signals PWRUP_2 to PWRUP-N are inputted to the second power-up signal generating unit 503. Each of the plurality of inter power-up detecting units 521 may be identically configured with the second power-up detecting unit 202 illustrated in FIG. 3, so that, for the sake of convenience, the explanation of the plurality of internal power-up detecting unit 521 will be omitted.

[0035] The second power-up signal generating unit 503 receives the first power-up signal from the first power-up detecting unit 501 and the plurality of internal power-up signals for the third power-up detecting unit 520. The second power-up signal generating unit 503 generates and outputs a final power-up signal PWRUP_SUM in response to the first power signal and the plurality of inter power-up signals.

[0036]FIG. 6 is a circuit diagram illustrating the second power-up signal generating unit 503 in the power-up signal generation circuit in accordance with another disclosed embodiment.

[0037] A source of a eighth PMOS transistor P61 is coupled to VDD and the first power-up signal from the first power-up detecting unit 201 is applied to a gate thereof. Sources of a plurality of NMOS transistor N6_1 to N6_N are coupled to VSS, their drains are coupled to a drain of the eighth PMOS transistor P61 and the plurality of power-up signals are applied to gates thereof.

[0038] A source of a ninth PMOS transistor P62 is coupled to VDD, its gate is coupled to VSS and its drain is coupled to a drain of the eighth PMOS transistor P61. The ninth PMOS transistor P62, whose gate is coupled to VSS, is always turned on and coupled to a fifth node node61. Namely, the ninth PMOS transistor P62 makes a DC path between the fifth node node61 and VDD, so that an initial voltage level of the fifth node node61 is maintained in VDD. At this time, considering a consumption current, the ninth PMOS transistor P62 is configured to a long channel transistor.

[0039] A drain and a source of a tenth PMOS transistor PCAP61 are coupled to VDD and its gate is coupled to a drain of the eighth PMOS transistor P61. An eighth inverter INV61 inverts a signal received through the drain of the eighth PMOS transistor P61 and outputs an inverted signal. Also, a ninth inverter INV62 inverts a signal received through an output of the eighth inverter INV61 and outputs an inverted signal. A tenth inverter INV63 inverts an output signal of the ninth inverter INV62 and outputs an inverted signal.

[0040] Hereinafter, an operation of the disclosed power-up signal generation circuits will be described.

[0041] The power-up signal generating unit 203 or 503 receives the first power-up signal outputted from the first power-up detecting unit 201 or 501 and the second power-up signal outputted from the second power-up detecting unit 202 or the plurality of internal power-up signals outputted from the third power-up detecting unit 520 and outputs the final power-up signal PWRUP_SUMP with a high level, which representing that the power supply voltage is correctly applied to the device. Even if the first power-up signal is not generated due to capacitor coupling, the final power-up signal is outputted with a high level in response to the second power-up signal or the plurality of internal power-up signals.

[0042] The reason that a fail does not occur in the second power-up detecting 202 or in the third power-up detecting 520 by coupling a capacitor structure, is that, even if VDD is slowly applied, the internal voltage V_(CORE) can be rapidly increased with a constant ramp up speed by an internal power supply voltage driving circuit (not shown). Also, the fourth node and the fifth node are initially a high state with VDD and then, if the second power-up detecting unit 202 and the third power-up detecting unit 520 detect an internal power supply voltage level, the level becomes VSS. As the result, the final power-up signal becomes from a low voltage state to a high voltage state. That is, it means that the operation is ready by the power supply voltage VDD applied from an external circuit.

[0043]FIG. 7 is a timing diagram showing for the disclosed power-up signal generation.

[0044] Referring to FIG. 7, if the external power supply voltage VDD is applied, the internal power supply voltage VCORE is activated. When the external power supply voltage VDD reaches to a critical level, the first power-up signal PWRUP1 of the first power-up detecting unit 201 is activated and then the voltage level thereof is increased to VDD. When the internal power supply voltage V_(CORE) reaches to a critical level, the second power-up signal PWRUP2 of the second power-up detecting unit 202 is activated and then the voltage level thereof is increased according to an increase of the internal power supply voltage V_(CORE).

[0045] If the first power-up signal inputted to the power-up signal generation unit 203 is a logic high level, a voltage level of the fourth node node41 is transited into a logic low level and the final power-up signal PWRUP_SUM activated by the power-up signal generation unit 203 is outputted.

[0046] If the first power-up signal inputted to the power-up signal generation unit 203 is a logic low level, generation of the final power-up signal PWRUP_SUM is determined according to a logic level of the second power-up signal. If the second power-up signal is a logic high level, the final power-up signal is generated and outputted by the power-up signal generation unit 203. If the second power-up signal is also a logic low level, the final power-up signal is not activated in the power-up signal generation unit 203.

[0047] Since the external supply voltage and the internal power supply voltage are employed, an error of operation of the power-up signal generation circuit can be prevented. Namely, even if the external power supply voltage level is slowly ramped up to a self voltage level, the power-up signal can be correctly generated.

[0048] While the disclosed circuits and devices have been described with respect to the particular embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of this disclosure as defined in the following claims. 

What is claimed is:
 1. An apparatus for generating a power-up signal, comprising: a first power-up detecting unit, to which an external power supply voltage is applied, for activating a first power-up signal when an increase of the external power supply voltage is detected; a second power-up detecting unit, to which an internal power supply voltage is applied, for activating a second power-up signal when an increase of the internal power supply voltage is detected; and a power-up signal generating means for activating a final power-up signal in response to combination of the second power-up signals.
 2. The apparatus as recited in claim 1, wherein the second power-up detecting unit comprises: a first PMOS transistor, whose source is coupled to the internal power supply voltage and gate is coupled to its drain; a second PMOS transistor, whose source is coupled to the drain of the first PMOS transistor and gate is coupled to ground voltage VSS; a first NMOS transistor, whose drain is coupled to the drain of the second PMOS transistor, gate is coupled to its drain and source is coupled to ground voltage VSS; a second NMOS transistor, whose drain and source are coupled to ground voltage VSS and gate is coupled to the drain of the second PMOS transistor; a third PMOS transistor, whose source is coupled to the internal power supply voltage and drain is coupled to the drain of the second PMOS transistor; a first inverter for inverting a signal received through the drain of the second PMOS transistor and for outputting an inverted signal to a gate of the third PMOS transistor; a fourth PMOS transistor, whose drain and source are coupled to the internal power supply voltage and gate is coupled to the gate of the third PMOS transistor; a second inverter for inverting a signal inputted through the gate of the fourth PMOS transistor; a third NMOS transistor, whose drain and source are coupled to ground voltage VSS and gate is coupled to an output of the second inverter; a third inverter for inverting a signal inputted from the second inverter; and a fourth inverter for inverting a signal inputted from the third inverter.
 3. The apparatus as recited in claim 1, wherein the power-up signal generating means comprises: a fifth PMOS transistor, whose source is coupled to the external power supply voltage, which the first power-up signal is applied to a gate thereof; a fourth NMOS transistor, whose source is coupled to ground voltage VSS and drain is coupled to the drain of the fifth PMOS transistor, which the second power-up signal is applied to a gate thereof; a sixth PMOS transistor, whose source is coupled to the external power supply voltage, gate is coupled to ground voltage VSS and drain is coupled to the drain of the fifth PMOS transistor; a seventh PMOS transistor, whose drain and source are coupled to the external power supply voltage and gate is coupled to the drain of the fifth PMOS transistor; a fifth inverter for inverting a signal inputted from the drain of the fifth PMOS transistor; a sixth inverter for inverting a signal inputted from the fifth inverter; and a seventh inverter for inverting a signal inputted from the sixth inverter.
 4. The apparatus as recited in claim 3, wherein the sixth PMOS transistor is a long channel transistor.
 5. An apparatus for generating a power-up signal, comprising: a first power-up detecting unit, to which an external power supply voltage is applied, for activating a first power-up signal when an increase of the external power supply voltage is detected; a second power-up detecting unit having a plurality of internal power-up detecting units, to which an internal power supply voltage is applied, for activating a plurality of power-up signals when an increase of the internal power supply voltage is detected; and a power-up signal generating means for receiving the first power-up signal and the plurality of power-up signals and for activating a final power-up signal.
 6. The apparatus as recited in claim 5, wherein the internal power-up detecting unit comprises: a first PMOS transistor, whose source is coupled to the internal power supply voltage and gate is coupled to its drain; a second PMOS transistor, whose source is coupled to the drain of the first PMOS transistor and gate is coupled to ground voltage VSS; a first NMOS transistor, whose drain is coupled to the drain of the second PMOS transistor, gate is coupled to its drain and source is coupled to ground voltage VSS; a second NMOS transistor, whose drain and source are coupled to ground voltage VSS and gate is coupled to the drain of the second PMOS transistor; a third PMOS transistor, whose source is coupled to the internal power supply voltage and drain is coupled to the drain of the second PMOS transistor; a first inverter for inverting a signal received through the drain of the second PMOS transistor and for outputting an inverted signal to a gate of the third PMOS transistor; a fourth PMOS transistor, whose drain and source are coupled to the internal power supply voltage and gate is coupled to the gate of the third PMOS transistor; a second inverter for inverting a signal inputted through the gate of the fourth PMOS transistor; a third NMOS transistor, whose drain and source are coupled to ground voltage VSS and gate is coupled to an output of the second inverter; a third inverter for inverting a signal inputted from the second inverter; and a fourth inverter for inverting a signal inputted from the third inverter.
 7. The apparatus as recited in claim 5, wherein the power-up signal generating means comprises: a fifth PMOS transistor, whose source is coupled to the external power supply voltage, which the first power-up signal is applied to a gate thereof; a plurality of fourth NMOS transistors, whose sources are coupled to ground voltage VSS and drains are coupled to the drain of the fifth PMOS transistor, respectively, which the plurality of power-up signals are applied to each gate thereof; a sixth PMOS transistor, whose source is coupled to the external power supply voltage, gate is coupled to ground voltage VSS and drain is coupled to the drain of the fifth PMOS transistor; a seventh PMOS transistor, whose drain and source are coupled to the external power supply voltage and gate is coupled to the drain of the fifth PMOS transistor; a fifth inverter for inverting a signal inputted from the drain of the fifth PMOS transistor; a sixth inverter for inverting a signal inputted from the fifth inverter; and a seventh inverter for inverting a signal inputted from the sixth inverter.
 8. The apparatus as recited in claim 7, wherein the sixth PMOS transistor is a long channel transistor. 